METHODS CORE: Project Summary/Abstract The Methods Core (MC) is organized to position the ASSIST Center (Accelerator Strategies for States to Improve System Transformations Affecting Children, Youth and Families) to support the identification of state policy dissemination targets and the development and testing of accelerator strategies to optimize the effectiveness of interventions and service delivery models for youth with serious mental health disorders (SMHD) and their families. The MC will support all activities of the ASSIST Center, including providing methodological support to all of the Center's investigators, including the large cadre of trainees (n=14) as well as the early and mid-career investigators who will co-lead and provide key contributions to our three planned research projects and four of the Core units. Working closely with the Administrative Core (AC), the MC will be a resource to all Center investigators and the national research community via three aims: Aim 1. Identify and develop rigorous, practical, and novel methods for state policy research for use by states, providers, health plans/payors, and youth and families. The MC will advance the development of innovative designs, methods, measurements and system science tools relevant to state policy research nationally. Where possible, the MC will capitalize on state Medicaid data, administrative data, and other publicly-available datasets to advance theory-driven, integrative, quantitative and qualitative methods for testing accelerator strategies to improve provider performance, quality measurement, and to inform state and health plan initiatives that unfold as healthcare shifts restructure the organization and delivery of state services. Aim 2. Provide operational support to Center investigators. The MC will ensure that all Center research projects and pilot research projects use rigorous design and analytic strategies through the experiences of the MC leadership, which includes expertise in epidemiology (Co-Lead Horwitz), quantitative methods and design (Co-Lead Gibbons), qualitative and mixed methods (Co-Lead Palinkas), and system science (Co-Investigator Luke). MC operational support will be provided through two units: (1) the Project Design and Analysis Services Unit (co-led by McGregor, an early career investigator, and Horwitz), which will provide design consultation, data collection and analyses, and Institutional Review Board training and support; and (2) the Data Coordination Unit (co-led by Brown, an early career investigator, and McKay), which will provide data management, quality assurance, and access to state and federal administrative data warehouses; and Aim 3. Disseminate methods, data, and tools nationally. The MC will work in coordination with the AC's Communications and Stakeholder Engagement Unit to be a national resource for pragmatic methods and tools for large-scale state policy research, and make available data to promote cross-state and cross-system collaborations, via dissemination strategies outlined in the AC.